Perfluoroalkyl substances (PFAS) are ubiquitous and persistent environmental contaminants, yet knowledge of their biological effects and mechanisms of action is limited. The highest aqueous PFAS concentrations are found in areas where bacteria are relied upon for functions such as nutrient cycling and contaminant degradation, including fire-training areas, wastewater treatment plants, and landfill leachates. This research sought to elucidate one of the mechanisms of action of PFAS by studying their uptake by bacteria and partitioning into model phospholipid bilayer membranes. PFAS partitioned into bacteria as well as model membranes (phospholipid liposomes and bilayers). The extent of incorporation into model membranes and bacteria was positively correlated to the number of fluorinated carbons. Furthermore, incorporation was greater for perfluorinated sulfonates than for perfluorinated carboxylates. Changes in zeta potential were observed in liposomes but not bacteria, consistent with PFAS being incorporated into the phospholipid bilayer membrane. Complementary to these results, PFAS were also found to alter the gel-to-fluid phase transition temperature of phospholipid bilayers, demonstrating that PFAS affected lateral phospholipid interactions. This investigation compliments other studies showing that sulfonated PFAS and PFAS with more than seven fluorinated carbons have a higher potential to accumulate within biota than carboxylated and shorter-chain PFAS.

Stormwater biofilters are being implemented widely in urban environments to provide green space, alleviate flooding, and improve stormwater quality.

Perfluoroalkyl substances (PFAS) are used in a variety of products and are ubiquitous in the environment. They have been found to associate with eukaryotic cell membranes and alter membrane properties. Bacteria are exposed to elevated concentrations of PFAS in some environments; nevertheless, the effect of PFAS exposure on microbial membranes has not yet been studied. Some quorum sensing pathways require the passive diffusion of signaling molecules through cell membranes. Quorum sensing initiates a variety of bacterial processes, such as biofilm formation and antibiotic production. If PFAS exposure increased the microbial quorum sensing response, these processes could be initiated at lower population densities, with wide-ranging ramifications for PFAS-impacted environments. This study examined the effect of perfluorinated alkyl sulfonates and carboxylates on quorum sensing in a model bacterium, Aliivibrio fischeri. Results showed that cultures exposed to PFAS were brighter after they received the signaling molecule. The observed increase in luminescence was dose-dependent and increased with the fluorinated carbon number. Specifically, perfluorooctanesulfonate increased luminescence at levels as low as 10 μg/L. PFASexposed bacteria were also more permeable to a semi-membrane permeable dye. Therefore, it is likely that increased permeability was, at least in part, the cause of increased luminescence.

This work determines the components of aqueous film forming foam responsible for disrupting microbial community functions.